<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .top {
            width: 600px;
            height: 600px;
            border: 1px;
            background-color: black;
            display: flex;
            /* justify-content: space-between; */
            align-items: center;
            justify-content: center;
        }

        .mid1 {
            width: 200px;
            height: 200px;
            border: 1px;
            background-color: yellow;
        }

        .mid2 {
            width: 200px;
            height: 200px;
            border: 1px;
            background-color: green;
        }
    </style>
</head>




<body>
    <div class="top">
        <div class="mid1"></div>
        <div class="mid2"></div>
    </div>
</body>

</html>